US Patent 8006589 Engine flywheel

In a flywheel in which narrow portions to be engaged with a coil spring included in the flywheel are formed of recessed portions made by recessing the surface of a flywheel cover, the portions of a sensor plate welded to the front cover, which confront with the recessed portions are made more fragile than adjacent portions of the sensor plate. With this configuration, when the front cover is deformed, stress applied to welded portions adjacent to the recessed portions can be suppressed since the fragile portions are easily deformed. Accordingly, even if the recessed portions are formed to the surface of a flywheel cover, stress can be prevented from being concentrated on the coupling portions of the flywheel cover and the sensor plate.